The present invention relates to an operation method of a controller for controlling an industrial machine such as a machine tool, and more specifically to an operation method of a controller having a processor, such as a CNC (computerized numerical control) apparatus for controlling a machine tool or a robot controller for controlling a robot.
In the CNC apparatus for controlling a machine tool and the robot controller for controlling a robot, a processor is used. There are cases where the processor causes a thermal runaway or elements thereof are destroyed by heat generated by the processor itself as the generated heat increases with an increase of consumed electric power in high-speed processing of the processor. A conventional method adopted for preventing the runaway and the destruction of elements is to improve heat radiation from the processor so as to prevent a rise in temperature of the processor using a heat sink and/or a fan. However, if a fan stops or efficiency of the heat radiation drops by inappropriate ventilation to rise the temperature of the processor abnormally, there is a possibility of causing the thermal runaway of the processor and further the thermal destruction. In order to avoid such possibility, the controller is alarm-stopped, driving of a motor of a machine which is drivingly controlled by the controller is stopped, and operation of the entire system is stopped.
As a method of preventing heat generation of a processor in the field of portable personal computers, there has been developed a computer having a processor capable of operating in a low electric-power-consumption mode for reducing heating.
Even if operation of the entire control system is stopped by stopping a motor when a stop of a fan or an abnormal temperature is detected, the temperature of the controller does not drop immediately. In some cases, there remains a risk that the processor would be destroyed by heating. Another problem is that such emergency stop due to a rise of temperature happens while a machine is working or operating, to require a long time to restore the machine after the emergency stop. Further, in CNC apparatuses and the like, when a motor stops and machining is interrupted, a workpiece being machined has to be abandoned. Furthermore, in unmanned operation, it is a problem that after an emergency stop, the control device does not operate for a long time, so that machining does not proceed.
An object of the present invention is to provide an operating method for a controller in which a rise in temperature of a processor is reduced, and control operation is restored and resumed easily even if the control operation is stopped due to the rise in temperature.
Another object of the present invention is to provide an operating method for a controller in which the controller continues its control operation by possibly preventing a stop of the operation.
According to one aspect of the present invention, a method of operating a controller comprises the steps of: detecting an operating state of a cooling fan for cooling an interior of the controller; detecting temperature inside the controller; and making the processor perform only minimum processing required for resuming a control operation thereof in the plurality of processings to be regularly performed by the processor in every predetermined period and operate in a low-electric-power consumption mode in a time period except the time period for performing the minimum processing when a stop of the cooling fan is detected or the detected temperature is higher than a set value.
According to another aspect the invention, a control method for a controller comprises the steps of: detecting a temperature inside the controller; and controlling the industrial machine by changing an operating speed of the industrial machine depending on the detected temperature to reduce a rise in temperature in the controller. Thus, a rise in temperature of the processor is reduced. In addition, a rise in temperature of the processor is reduced by reducing luminous energy of a back light provided in a display device or turning off the back light or by changing an acceleration/deceleration time constant for a motor controlled by the controller.